/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.sparql.function.library;

import java.util.List;
import java.util.StringJoiner;

import org.apache.jena.sparql.expr.ExprList;
import org.apache.jena.sparql.expr.NodeValue;
import org.apache.jena.sparql.function.FunctionBase;

/**
 * Function that prints the system time to stderr at the point of execution. Returns
 * true. This is a debugging aid only.
 */
public class execTime extends FunctionBase {

    static long lastms = -1;

    @Override
    public NodeValue exec(List<NodeValue> args) {
        long now = System.currentTimeMillis();
        StringJoiner sj = new StringJoiner(" ", "", "");
        args.forEach((a) -> {
            sj.add(a.asString());
        });
        if ( lastms != -1 )
            sj.add("(" + Long.toString(now - lastms) + ")");
        String str = sj.toString();

        if ( !str.isEmpty() )
            System.err.printf("%s : %d ms\n", str, System.currentTimeMillis());
        else
            System.err.printf("---- %d ms\n", System.currentTimeMillis());
        lastms = now;
        return NodeValue.TRUE;
    }

    @Override
    public void checkBuild(String uri, ExprList args) {}
}
